In rotary regenerative heat exchange apparatus a mass of heat absorbent material is positioned in a hot gas stream to absorb heat from hot gases passing therethrough. After the heat absorbent material becomes heated by the hot gases it is moved to a stream of cooler air or other gas where the then hot material transmits its newly absorbed heat to the cool fluid passing therethrough.
The heat absorbent material is usually carried in a rotor that rotates between the hot and cool fluids, while a fixed housing including sector plates at opposite ends of the rotor is adapted to surround the rotor. To prevent mingling of the hot and cool fluids, the end edges of the rotor are provided with flexible sealing members that rub against the adjacent surface of the rotor housing to resiliently accommodate a limited degree of "rotor turndown" or other distortion caused by mechanical loading or thermal deformation of the rotor.
To permit turning the rotor freely about its axis, certain minimum clearance space between the rotor and adjacent housing is to be desired, however, excessive clearance must be avoided to preclude excessive fluid leakage. Under conditions marked by a rapid change of temperature, however, excessive deformation of the rotor may cause excessive leakage and a reduction in the overall effectiveness of the device, while excessive interference between the rotor and adjacent housing structure may cause excessive wear.
The expansion of the rotor and the adjacent rotor housing assumes the greatest proportions directly adjacent the inlet for the hot fluid where the change in temperature similarly assumes maximum proportions. In accordance with U.S. Pat. No. 4,124,063 the sector plate was forced by a mechanical actuator to assume a dished configuration similar to that of the rotor whereby there would be a minimum of clearance therebetween.
An arrangement disclosed by U.S. Pat. No. 4,206,803 moves the sector plate with a geared actuating rod in response to a particular sensor. This system utilizes a geared actuating rod that is relatively expensive to provide, difficult to install and, moreover, unreliable for continuous operation.